A conventional variable capacity type vane pump is known which varies the eccentricity of a cam ring with respect to a rotor to vary a discharge capacity by pivoting the cam ring about a pin.
JP2003-74479A discloses a variable capacity type vane pump in which a first fluid pressure chamber, in which a fluid pressure is controlled by the operation of a control valve, is provided at one side in a pivoting direction of a cam ring and a second fluid pressure chamber, to which a suction side pressure is introduced, is provided at the other side. This variable capacity type vane pump is so designed that the cam ring pivots in a direction to decrease a discharge capacity if the fluid pressure in the first fluid pressure chamber is increased by the operation of the control valve.